This application claims the priority of German application 198 18 780.0, filed in Germany on Nov. 2, 1998, and German application 199 18 780.0 filed in Germany on Apr. 26, 1999, the disclosures of which are expressly incorporated by reference herein.
The present invention relates to a process for monitoring the hairiness of yarns, spun on ring spinning machines comprising condensing devices and wound onto cops, and for initiating various measures dependent on the hairiness ascertained.
Ring spinning machines comprising condensing devices are prior art in, for example, U.S. Pat. No. 5,600,872. Condensing devices of this type are located at each spinning station directly downstream of the respective drafting arrangement in a zone, to which the spinning twist imparted by the ring spindle does not retroact. The particular feature of yarn spun on ring spinning machines comprising condensing devices is the low hairiness. Differing degrees of hairiness can be ascertained just by visually comparing two cops.
By means of the condensing device, outwardly projecting edge fibers of the drafted fiber strand are rolled pneumatically around the core strand, which results in the fiber strand being condensed. If the fiber strand has been condensed well, no fiber triangle occurs at the last nipping line, to which point the spinning twist returns. In contrast thereto, in the case of a standard ring spinning machine without condensing device, there is a fiber triangle present. In this case the edge fibers are not sufficiently rolled in, and thus a hairy yarn arises. The wider the fiber triangle is, the hairier the yarn.
If, for some reason, condensing does not, or does not fully, take place in the case of ring spinning with condensing devices, an undesirable fiber triangle occurs at the respective spinning station. Such defects cannot unfortunately be eliminated by means of pneumatic condensing, as suction devices may become blocked by fiber fly, or fiber fly may settle in the suction openings present in a condensing device, so that the desired condensing does not takes place in the desired way. This is in particular the case when dirty cotton is processed, in particular when it contains so-called honeydew.
Cops which are formed from such faulty spinning stations are extremely dangerous. Mixed in with good cops, they can result in faults in the end product, for example a woven fabric, which can render the product unmarketable. The otherwise even product becomes streaked, or the so-called Moir effect can arise due to the differing degrees of hairiness. Different degrees of hairiness can result in uneven color when dyeing. An increased hairiness in the yarn of a single cop can cause a whole batch of woven fabric to be rejected.
In spinning mills using ring spinning machines comprising condensing devices, the individual cops were up to now manually examined and the unusable ones rejected. This process is not economically viable in the case of mass production of yarns.
It is an object of the present invention therefore to make the process for monitoring the hairiness in ring spinning machines comprising condensing devices of the above mentioned type more economically viable and to ensure that for one and the same end product only cops having yarns without varying degrees of hairiness are used.
This object has been achieved in accordance with the present invention in that at least one monitoring station is connected to the ring spinning machine, in which monitoring station the yarn is automatically checked for hairiness and the cops are automatically sorted out according to the monitoring results.
By applying the process according to the present invention, the yarn of each individual cop is monitored. A monitoring station of this kind functions preferably optically and is so designed that each cop, for example, stands out well from a dark background wall, so that outwardly projecting hairs are easily recognized by the monitoring station.
The process can be particularly easily carried out when the cops are monitored during transport away from the ring spinning machine according to certain preferred embodiments of the invention. Monitoring must occur at the latest before the cops are re-wound to cross-packages and could, in certain circumstances, even take place at the winding machine. The cops transported away from the ring spinning machine can be transported to travel through a monitoring station. According to the degree of hairiness, the cops can then be individually rejected or classified.
Although monitoring can be carried out while the cops are travelling, it is particularly advantageous according to certain preferred embodiments of the invention when the cops are guided through the monitoring station by means of a preferably sequenced-motion transport device, for example peg trays. The further transportation of the peg trays from the ring spinning machine occurs, as a rule, periodically, whereby in each sequence the cops come to a short standstill. This short standstill is sufficient time for the optical monitoring of the cops by means of a light flash. If the monitoring station is too slow, a plurality of monitoring stations can be activated one after the other with each monitoring station being given the function to check the cop only at a certain point. It is important in this respect that the monitoring station ascertains from which spinning station of the ring spinning machine the respective cop comes.
When the cops are being monitored during a standstill, it is purposeful to set up a buffer zone between the ring spinning machine and the winding machine according to certain preferred embodiments of the invention. By these means, more monitoring stations can be arranged adjacent to one another, into which the cops can be placed. They can then remain there for some seconds and subsequently be transported further by the transport device. When a plurality of cops are monitored at the same time, a short standstill, which is longer than the sequence time of the transporting device, does not have a negative effect.
A buffer zone during a peg tray transport can also be realized in that the closed chain of the peg tray row is broken by a gap, and that in the area of this gap, the transport of several peg trays, for example six, is accelerated by means of a rapid motion according to certain preferred embodiments of the invention. These six peg trays have at their disposal an extended dwell time, namely until the gap is closed again by the normal peg tray transport. This is explained in more detail below in the description of the Figures.
Spinning cops having an undesirably high degree of hairiness must not necessarily be rejects. In a further feature of preferred embodiments of the present invention, the cops can be classified according the degree of hairiness and used for various purposes. The sorting of the cops takes place hereby according to various monitoring criteria. In the case of a very important and high quality batch, for example, the monitoring station is adjusted to be more exact than for a normal batch. For a product of particular quality, different standards of quality could be classified, and only the very bad quality cops would be rejected as unusable.
In particular in the case of link systems between ring spinning machines and winding machines, removing cops which appear unsuitable from the transporting device presents no difficulties. It is possible for removal from the transporting device to take place at a later point in time, that is at the winding machine, according to certain preferred embodiments of the invention. What is important is that either the cop is accordingly marked, or the computer knows, by means of counting, at which point of the transporting device a bad cop is located.
In practice it is provided that the faulty spinning stations are identified retroactively and indicated by a computer according to certain preferred embodiments of the invention. At the latest at the winding machine, advantageously however before that, the spinning stations of the ring spinning machine which have created a yarn which is too hairy are ascertained and indicated. When a spinning station has been indicated as being qualitatively bad, the operating personnel must be informed in a suitable way, for example by way of a number indicator or by the lighting of a control lamp at the respective spinning station. The operating personnel can then check whether suction openings or other places in the revelant condensing device are no longer sufficiently air permeable.
Monitoring in the monitoring station should be carried out regardless of the degree of fullness of the cops according to certain preferred embodiments of the invention. The possibility exists that a yarn is differently hairy at the beginning of a spinning operation or at its end. This can be ascertained in the monitoring station when a cop is tested for hairiness over its entire length.
It is purposeful when the cop is rotated around its axis in the monitoring station according to certain preferred embodiments of the invention. Thus gives still more reliable values. For example, a small auxiliary motor could, by means of a friction wheel, cause the supporting device of the respective cop to rotate.
After the cops have been produced, there is always the risk that the hairs present are pressed on by means of a component or by manual contact. In order that the monitoring results are not falsified, it is provided in a further feature of preferred embodiments of the present invention that a stream of air is passed over the cops in to order to make the hairs stand up in the monitoring station.
The hairiness of the yarn does not necessarily have to be monitored in a wound state of the cops according to certain preferred embodiments of the invention. The monitoring station can function in such a way that a sufficiently long piece of yarn for monitoring is taken off the wound cop. The cop is then processed further thereafter. This type of monitoring is, however, when it takes place outside of the winding machine, more complicated than the monitoring of the cop itself.
Alternatively, according to certain preferred embodiments of the invention, the yarn can be also only tested for hairiness at the winding machine during rewinding, as long as it is certain that the defect spinning stations are detected by suitable means. The yarns can, in this case, travel through a monitoring station at each work station of the winding machine, which monitors the respective yarn for hairiness. Thus no time loss occurs, as the yarns are wound off the cops anyway during rewinding.
In another process according to the present invention, the yarns are already monitored for hairiness during the spinning process, advantageously by means of a maintenance device which travels along the length of the ring spinning machine, to which maintenance device the monitoring station is applied. In ring spinning, a so-called yarn balloon occurs, on which, under the action of the occurring centrifugal forces, the hairs spread so that they can be seen very clearly. When a stroboscope is arranged at the monitoring station, the yarn balloon appears to the monitoring station to stand still. This results in the monitoring station having sufficient time for monitoring. In addition, the yarn is monitored repeatedly in this process during a cop winding. Finally, the spinning process can be stopped on the spot if required in the case of inadmissible hairiness.
There are monitoring devices already on the market for measuring hairiness, which have never been connected with a ring spinning machine up to now. These measuring devices function using, for example, a digital camera, whose signals are taken up by a computer and analyzed, or by means of line diodes, whose values are processed by a computer.
For the process according to certain preferred embodiments of the present invention, a digital camera, the principles of which are known, is advantageously used, in which a computer, designed expressly for image evaluation, is integrated. The computer comprises a plurality of entries and exits, by means of which the monitoring station can be controlled. The digital camera is programmed in such a way that it functions as though a plurality of line diodes were laid out together at certain distances. The camera is arranged on the one side of the thread or cop, and the necessary lighting on the other side of the thread or the cop.